Webber heads final practice as Vettel suffers KERS issue

Mark Webber set the fastest time during final practice at the Japanese Grand Prix as Red Bull team-mate Sebastian Vettel had to sit out of half of the session with a KERS problem.

After 11 laps Vettel, who could sew up his fourth world championship this weekend, saw his car go up on jacks in the garage as his rivals went on track for low-fuel qualifying simulation runs on the medium compound tyres. By the end of the session he had dropped to ninth, albeit only a tenth of a second off Kimi Raikkonen's medium tyre lap, but it was the first sign of a possible chink in the armour at Red Bull.

Lewis Hamilton got closest to Webber's fastest time of 1:32.053, with a lap 0.134s off as we look set for a Mercedes versus Red Bull battle for pole position. Nico Rosberg was third fastest and 0.302s off Webber, but came across traffic towards the end of his fast lap.

Romain Grosjean was at the wheel of the fastest Lotus after testing the limits throughout the session with several journeys into the tarmac run-off areas. However, he and team-mate Raikkonen appeared to be on different programmes to their rivals, completing eight of nine laps more than the average driver and moving onto the medium tyre earlier in the session.

Jenson Button again showed McLaren's potential this weekend with the seventh fastest time, just 0.816s off Webber's best. He was faster than Raikkonen and Vettel, although for the reasons mentioned above is likely to find himself back behind them in qualifying.

Nico Hulkenberg continued his fine form with the tenth fastest time ahead of Sergio Perez and the Toro Rossos, in what looks likely to be a tight fight for the final positions in Q3.

But it wouldn't be a Suzuka practice session without at least one driver finding the barrier, and this time it was Adrian Sutil who was caught out by the perils of the circuit. As he accelerated out of Spoon corner the rear of his Force India stepped out and he slid to the inside of the corner where the nose of the car was wiped off by the barrier. Of more concern for the Force India mechanics, however, was the thwack the rear suspension took as the car spun round after its first impact.

Both Force India and Red Bull had two hours from the end of the session to set their cars right for qualifying.